{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{6}{c}}
\hline\hline
                    &\multicolumn{3}{c}{Sub-Saharan African societies}             &\multicolumn{3}{c}{All other societies}                       \\\cmidrule(lr){2-4}\cmidrule(lr){5-7}
                    &\multicolumn{1}{c}{(1)}        &\multicolumn{1}{c}{(2)}        &\multicolumn{1}{c}{(3)}        &\multicolumn{1}{c}{(4)}        &\multicolumn{1}{c}{(5)}        &\multicolumn{1}{c}{(6)}        \\
\hline
Pre-colonial suitability of Soil for Agriculture&       -0.01        &       -0.15        &       -0.08        &        0.11\sym{*} &        0.07        &        0.05        \\
                    &      (0.15)        &      (0.13)        &      (0.11)        &      (0.06)        &      (0.05)        &      (0.05)        \\\hline
Pre-colonial population density&                    &        0.40\sym{**}&      0.26\sym{\dag}&                    &        0.17\sym{**}&        0.05        \\
                    &                    &      (0.14)        &      (0.12)        &                    &      (0.06)        &      (0.07)        \\\hline
Pre-colonial political centralization&                    &                    &        0.41\sym{**}&                    &                    &        0.27\sym{*} \\
                    &                    &                    &      (0.12)        &                    &                    &      (0.12)        \\
Latitude in Degrees &                    &                    &        0.00        &                    &                    &        0.00        \\
                    &                    &                    &      (0.01)        &                    &                    &      (0.00)        \\
Longitude in Degrees&                    &                    &       -0.01        &                    &                    &        0.00        \\
                    &                    &                    &      (0.01)        &                    &                    &      (0.00)        \\
\hline
Societies (N)       &          20        &          20        &          20        &          70        &          70        &          69        \\
\(R^{2}\)           &        0.00        &        0.34        &        0.64        &        0.06        &        0.18        &        0.28        \\
Adj. \(R^{2}\)      &       -0.06        &        0.26        &        0.51        &        0.04        &        0.16        &        0.22        \\
\hline\hline
\end{tabular}
}
